1. Technical Field
The invention relates to the field of communication systems and particularly to systems for frequency spread bandwidth allocation.
2. Background Art
Many communication systems have ever increasing problems with available spectrum. There are many problems associated with the lack of radio frequency (RF) spectrum. Interference associated with many systems is a significant cause of lack of spectrum bandwidth. The present invention is believed to dramatically improve the spectrum allocation and re-use by using interference detection, discrimination and rating techniques and methods. The techniques go beyond the known frequency policy methods and hardware implementations that have been used in the past as well as those currently being used.
Traditional co-site interference can be described as Radio Frequency (RF) energy present within a set area or facility that causes interference and degradation of communication links and systems. Internal interference sources consist mostly of fundamental RF power, broadband noise, and spurious transmissions originating from co-located transmitters. These transmissions not only interfere with defined communication channels and frequencies, but also degrade and reduce the overall available spectrum that is not used at any particular time.
Traditional co-site solutions consist of complex and unique hardware implementations of antenna directivity, agile RF filtering and combining with other high power techniques, such as interference cancellation phase inversion systems (also known as ICS systems). These solutions are geared toward solving the problems within the platform defined RF channels and frequencies respectively.
RF Interference that does not originate within a given site by design or “as is” can be described as interference that is external or unknown. Sometimes this type of interference can be described as non-directed innocent transmissions or can also be described as directed or hostile transmissions. Intentional jamming is a directed intentional interferer. The dynamic spectrum utilization (“DSU”) methods and techniques of the present invention can help differentiate the sources of interferences as described subsequently. The differentiation augments frequency management systems that otherwise may make incorrect decisions on where a communication system may or may not transmit in. Interference blind re-try methods are usually very poor in trying to re-establish a link failure or a link's data performance.
There are many forms of normal RF interference that are not intentionally intended to interfere with communications systems. Typical sources are existing communication systems such as TV and FM transmissions, mobile communication systems such as Cellular systems, municipality transmission systems such as police, fire and rescue, general aviation, and air traffic control radar and guidance. Recently, the family radio service (“FRS”) bands are also sources of new external interference. Additionally, government and military systems, as well as other systems, may be causes of interference. These systems are usually well enough defined that they can be discriminated from one another by known signal processing techniques.
Hostile interference can be described as transmissions that are intentionally intended to disrupt, degrade, cause failure or destroy communication systems. These can be categorized into rough transmissions by individuals or tactical jamming systems developed by militaries and nations. The present DSU methods and techniques discriminate these intended transmissions.
Many other sources of interference can be identified. Items such as power-lines, computers and machinery can cause interference. Many of these can be mitigated by standard electronic design practices such as power supply de-coupling, filtering, and mechanical shielding techniques. These will not be extensively referenced herein, but should be similarly addressed by the present invention. The majority of the present DSU methods will describe and discriminate the aforementioned sources of interference as a method to improve the allocation and usage of available spectrum.
All communication links also have range or distance limitations. These are dependent on things such as transmit power, receiver sensitivity, bandwidth, antenna gains and channel coding. When observing and classifying interference on a communications system, it is usually ideal to limit measured interference to emissions that are above the range and Signal to Noise requirements of the system in question. These limitations are used in formulating smart thresholds when rating available spectrum for a given communication link and its corresponding present range.
For example, in an end to end mobile communication system, as the pair gets closer to each other, the sensitivity requirements of each receiver unit or end gets easier to understand. By dynamically adjusting the availability threshold level when classifying whether a channel is available or not allows one to classify not only the sensitivity requirements of the receiver, but that of the transmitter as well. The ratings are based on the time—distance relationship of the link which better serve frequency allocation sub-systems decision processes.
Terrain limitations on communications links are usually defined as an obstruction such as a building, mountain or vegetation such as a forest. This limitation can be addressed with GPS coordinated mapping techniques and augmented by a number of methods such as ground or airborne relay sub-systems. Link failures in these cases are not attributed to available spectrum, but to physical terrain.
While the above cited references introduce and disclose a number of noteworthy advances and technological improvements within the art, none completely fulfills the specific objectives achieved by this invention.